What is the appropriate evaluation and management of a patient with a head injury, particularly one who is taking anticoagulant therapy, such as warfarin (Coumadin) or aspirin?

Evaluation of Head Injury in Anticoagulated Patients

Immediate Imaging is Mandatory

All patients on anticoagulants (warfarin, NOACs) or antiplatelet agents (clopidogrel, aspirin plus clopidogrel) who sustain head trauma require immediate non-contrast head CT, regardless of mechanism severity or presence of symptoms. 1

• Anticoagulated patients have a 2.6-fold increased risk of significant intracranial injury (3.9% vs 1.5% in non-anticoagulated patients) 1, 2
• Warfarin carries the highest risk at 10.2% for intracranial hemorrhage, while NOACs carry a 2.6% risk 2
• Patients on warfarin alone have a relative risk of 1.88 for significant intracranial injury 1
• Combined aspirin and clopidogrel therapy carries the highest risk with a relative risk of 2.88 1
• Aspirin monotherapy does not significantly increase risk (relative risk 1.29,95% CI 0.88-1.87) and is not considered a factor requiring mandatory imaging by itself 1

Risk Stratification by Medication Type

High-Risk Medications Requiring CT:

• Warfarin: Obtain CT regardless of mechanism 1, 2
• NOACs (apixaban, rivaroxaban, dabigatran): Obtain CT regardless of mechanism 3, 2
• Clopidogrel alone or combined with aspirin: Obtain CT regardless of mechanism 1

Lower-Risk Medications:

• Aspirin monotherapy: Does not mandate CT unless other high-risk features present (age >65 years, GCS <15, loss of consciousness, post-traumatic amnesia, vomiting, headache) 1, 4

Management Algorithm for Positive Initial CT

If Intracranial Hemorrhage Detected:

1. Immediately discontinue anticoagulation 5, 2

2. Obtain immediate neurosurgical consultation 5

3. Reverse anticoagulation urgently:

   • Warfarin: Administer 4-factor prothrombin complex concentrate (4F-PCC) plus 5mg IV vitamin K to achieve INR <1.5 5, 2
   • Apixaban/rivaroxaban: Administer andexanet alfa if available; if unavailable, use 4F-PCC 3, 2
   • Dabigatran: Administer idarucizumab 3
   • Enoxaparin (if given within 8 hours): Administer 1mg protamine per 1mg enoxaparin (maximum 50mg) by slow IV over 10 minutes 5

4. Administer tranexamic acid 1g IV over 10 minutes if within 3 hours of injury (reduces head injury-related death, risk ratio 0.78) 5, 2

5. Obtain repeat head CT within 24 hours, as anticoagulated patients have a 3-fold increased risk of hemorrhage expansion (26% vs 9%) 5, 3, 2

6. Monitor neurologically with documented half-hourly checks until stable 5

Management Algorithm for Negative Initial CT

Discharge Criteria (All Must Be Met):

Patients with negative initial CT can be safely discharged without repeat imaging or observation if: 1, 3

• Neurologically intact at baseline examination 1, 3
• Glasgow Coma Scale score of 15 1
• No loss of consciousness or post-traumatic amnesia 1
• Adequate social support for home observation 3
• Clear discharge instructions provided 3, 2

The risk of delayed intracranial hemorrhage requiring intervention after negative initial CT is extremely low (<1%) in neurologically intact patients. 1, 3

Evidence Supporting Safe Discharge:

• Delayed ICH after negative initial CT occurs in only 0.6% of warfarin patients (95% CI 0.2%-1.5%), with none requiring neurosurgical intervention 1
• Zero patients on clopidogrel developed delayed ICH requiring intervention 1
• Only 1.5% of NOAC patients developed delayed ICH on repeat scanning, and none required neurosurgical intervention or died 3

Continue Anticoagulation After Negative CT:

Do not routinely discontinue anticoagulation or antiplatelet medications after negative initial CT in neurologically intact patients, as thromboembolic risk may outweigh the small risk of delayed hemorrhage 3, 2

Special Populations Requiring Closer Monitoring

Elderly Patients (≥65 years):

• Consider brief observation (4-6 hours) if age >80 years with loss of consciousness or amnesia 3
• Elderly patients on aspirin with high-risk features have a 4% risk of delayed ICH 3

Patients Requiring Observation Despite Negative CT:

• GCS <15 at presentation 1
• Persistent altered mental status 3
• Inadequate social support for home monitoring 3
• Age >80 years with loss of consciousness 3

Discharge Instructions (Critical Components)

Provide written instructions including: 3, 2

• Warning signs requiring immediate return: severe headache, confusion, vomiting, weakness, seizures, worsening drowsiness, slurred speech, vision changes, inability to wake 2
• Arrange responsible adult observation for 24 hours with specific monitoring instructions 2
• Outpatient follow-up for fall risk assessment and reassessment of anticoagulation risk/benefit ratio 5, 3

Common Pitfalls to Avoid

• Failing to obtain initial CT in patients on warfarin, NOACs, or clopidogrel after any head trauma 1, 3
• Performing unnecessary repeat imaging in stable patients with negative initial CT and normal neurological exam 3
• Discontinuing anticoagulation unnecessarily without considering thromboembolic risk 3, 2
• Delaying repeat imaging when any neurological deterioration occurs 5, 3
• Assuming aspirin monotherapy requires the same management as other anticoagulants (it does not unless other high-risk features present) 1, 4

Mortality Data Supporting Aggressive Management

• Anticoagulated patients with intracranial injury have a 4-5 fold higher risk of death than non-anticoagulated patients (38% vs 8% mortality) 6
• Aspirin alone in head-injured patients resulted in 47% mortality in one study, though this was not statistically different from warfarin 6
• However, low-dose aspirin (81mg) does not increase surgically relevant bleeding in patients >60 years with mild-moderate head injury 4